Bridgeless PFC Current-Sensing Control for Zero-Voltage Turn-On
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing bridgeless PFC circuits face challenges with high voltage fluctuations in switch elements, requiring stringent sampling control and weak signal anti-interference capabilities.
Innovation Solution
A bridgeless PFC circuit with a control module that collects current through a current sampling element, controlling the switch element to turn on based on the current threshold, thereby implementing zero-voltage turn-on and enhancing signal anti-interference capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage of switch element is detected to generate control signal, then zero-voltage turn-on of switch element is achieved, but sampling control circuit requires high performance and has weak signal anti-interference capability
Solution Approach 1:
The patent introduces a current sampling element as an intermediary to indirectly obtain switch element current information, avoiding direct voltage sampling. This mediator converts the difficult voltage measurement into easier current measurement, reducing the performance requirements of the sampling control circuit while maintaining zero-voltage turn-on capability
Solution Approach 2:
The patent replaces the voltage-based control mechanism with a current-based control mechanism. By substituting voltage detection with current detection through the sampling element, the system achieves the same control objective with simpler circuit requirements and better anti-interference performance
2Ease of operation
If voltage of switch element is detected for control signal generation, then switch element turn-on control is achieved, but delay requirement on sampling control circuit is high
Solution Approach 1:
The patent substitutes voltage-based timing control with current-based timing control. Since current changes more gradually than voltage, the sampling control circuit has more time to accurately detect and respond, significantly reducing the delay requirement while maintaining proper switch element control timing
3Productivity
If voltage of switch element is detected, then control signal is generated, but signal anti-interference capability is weak
Solution Approach 1:
The current sampling element serves as a mediator that provides a more stable and interference-resistant signal source. By measuring current through this dedicated sampling element rather than detecting voltage directly from the switching node, the system achieves better noise immunity and signal integrity
Solution Approach 2:
The patent changes the measurement parameter from voltage to current. Current signals inherently have better anti-interference characteristics in power conversion circuits, and by monitoring current through the sampling element, the system achieves more reliable control signal generation with reduced susceptibility to electrical noise and interference
Data Source
Figure 1~2
Figure 3~4
Figure 4a~5
AI summary
A bridgeless PFC circuit includes: A control module collects a current flowing through a current sampling element; and when the current flowing through the current sampling element is greater than a first threshold, the control module controls a switch element to be turned on. Based on the current flowing through the current sampling element, the switch element can be controlled to be turned on, thereby implementing zero-voltage turn-on of the switch element. Because the collected current does not change abruptly, a delay requirement on a sampling control circuit included in the control module is lowered, and a signal anti-interference capability of the control module is strong.